Asbestos investigation under way El Dorado, Ca. USA

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http://pubs.acs.org//journals/esthag-w/2003/nov/science/rr_asbestos.htm\

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Science News - November 13, 2003

Asbestos investigation under way

 

After years of local controversy over the health risks from naturally occurring

tremolite asbestos (Environ. Sci. Technol. 1999, 33, 348A–349A), a federal

agency on October 20 began an investigation in one of the fastest growing

regions of California. Some researchers believe that the study might reveal a

major public health problem.

 

The U.S. Agency for Toxic Substance Disease Registry (ATSDR) comes to El Dorado,

a suburb of Sacramento, with experience investigating the effects of tremolite

exposure in Libby, Mont. In Libby, tremolite asbestos occurs as a contaminant in

vermiculite that was mined primarily for use as insulation. Asbestos exposure in

the small town of about 12,000 has led to 192 deaths and has sickened hundreds

of others, according to a 2001 story by the Seattle Post-Intelligencer.

 

Tremolite asbestos has long been known to promote mesothelioma, a rare cancer of

the lining of the lung. A U.S. EPA expert panel in February 2003 unanimously

agreed that the carcinogenic potency of tremolite fibers is 2 orders of

magnitude greater than for chrysotile fibers. EPA is currently reevaluating its

1986 assessment of asbestos toxicity, which considers all asbestos fibers to be

equally hazardous. The ATSDR health evaluation will use this assumption.

 

Some asbestos health experts familiar with both places believe that El Dorado

County, whose population is projected to grow to more than 200,000 in the next

10 years, has the makings of a much bigger tragedy. “Thirty years from now,

everybody will forget Libby—but El Dorado will be one of the greatest public

health disasters of the 21st century in the United States” if development

continues unchecked, says pathologist and epidemiologist Bruce Case at McGill

University in Montreal, Canada. El Dorado’s population is 10 times that of

Libby, and tremolite asbestos is widespread near the surface. Activities that

stir up the soil can lead to exposure. In Libby, exposure came from vermiculite

mining operations, which lofted tremolite into the air. Miners are also thought

to have brought tremolite into their homes on their clothes.

 

Pathologist Jerrold Abraham at the State University of New York’s Upstate

Medical University recently found extremely high concentrations of asbestos

fibers in the lungs of a dog that had lived in El Dorado for more than 13 years.

The data are slim, but they indicate that it is likely that substantial human

exposures in this area have already occurred, he says. Since it takes decades

for mesothelioma to develop, such lung data may be one of the few ways to

predict the future.

 

New studies of Libby residents show that exposure to tremolite asbestos also

causes a range of respiratory illnesses, says EPA scientist Christopher Weis,

who collaborated on a 2000-2001 clinical study in which about 6800 Libby

residents had chest X-rays. About 18% of the population had scarred lungs,

including about 40% of men over 65 (Environ. Health Persp. 2003, 111,

1753–1759). “Nothing like this has ever been recorded before,” says Weis. “The

results really rocked us; we were completely surprised.”

 

The California Air Resources Board (CARB) has been monitoring the air in the El

Dorado region since 1998. However, CARB has mainly conducted ambient air

monitoring above the human breathing zone and not disturbed the soil, so the

organization’s data may not be relevant, says ATSDR’s regional representative

Libby Levy.

 

Recent experiences with amphibole asbestos in Libby and in the World Trade

Center cleanup have demonstrated the need for aggressive sampling to get an

accurate reflection of exposure, says Arnold Den, senior science adviser for

EPA’s Region 9. An aggressive sampling campaign requires stirring up the ground

and sampling at the breathing zone level. For example, when technicians used a

tractor rake to drag the baseball infield and the dirt track surrounding the

football field of the local Oak Ridge High School in July, some results exceeded

worker safety exposure limits. In August, the school’s football stadium and

baseball diamond were closed, and they have yet to be reopened.

 

Scientists interviewed for this story and many citizens worry that local

authorities fail to realize the magnitude of the problem and that federal

authorities can’t act because they believe they don’t have jurisdiction over a

naturally occurring problem.

 

No one wants a repeat of what happened in Libby. A May 2003 General Accounting

Office report criticized EPA for underestimating the extent of contamination in

Libby when citizens first complained in 1982. EPA only began an extensive

investigation and cleanup after media reports called attention to the health

disaster, according to the report. —REBECCA RENNER

 

 

 

 

2003 American Chemical Society

 

 

 

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